This invention relates to a display device comprising a polymer dispersed liquid crystal film. More particularly, this invention relates to such display device wherein the polymer dispersed liquid crystal film is optically coupled to an asymmetric optical diffuser to enhance contrast in the display.
A polymer dispersed liquid crystal film, also referred to as a PDLC film, comprises microdroplets of a liquid crystal material dispersed within a transparent polymeric matrix. Transparent electrodes are applied to opposite surfaces of the film. In the absence of an electric field, the liquid crystal microdroplets diffuse light, so that the film is translucent. However, an electric field applied between the electrodes orients the liquid crystal molecules to allow the film to transmit light without diffusion, so that the film becomes transparent.
It has been proposed to utilize PDLC film in forming a display. This is accomplished by patterning at least one electrode to switch a selected region of the film from the translucent condition to the transparent condition. However, displays formed with PDLC film suffer from poor contrast. This is attributed to light randomly scattered toward the viewer from translucent regions adjacent to a transparent region. This poor contrast limits image resolution, particularly in small displays. Thus, there remains a need to enhance contrast in PDLC displays.